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G factor

Scores on a wide range of intelligence tests tend to correlate positively. From a statistical or psychometric point of view this creates a variable, g that merely indicates the strength of this correlation. If there were no correlation at all, there would be no g, but since the correlations tend to be high, people get excited and many of them take the next step of positing an underlying common cause (also called g). For the psychologists who defend this notion, there is a common variable (modulating, say, the way your neurons fire) that influences on the measures of all of these intelligence tests, thus creating the observed correlation. However researchers from the University of Amsterdam are challenging the common wisdom and suggest an explanation for the correlation that doesn’t need a common cause.